Prismatic and cylindrical cutting inserts

ABSTRACT

A prismatic and cylindrical cutting insert for long edge rotary milling applications has multiple indexable cutting edges ranging from four to six or even more depending on the actual milling applications. Each cutting edge of a prismatic or cylindrical cutting insert provides a positive cutting geometry and is equivalent to an indexable cutting edge of a traditional single-sided parallelogram-shaped cutting insert having two indexable cutting edges (often referred as A-Style insert). The prismatic and cylindrical (including tapered or conical) cutting insert may be used for machining a wide range of materials including difficult-to-machine materials, cast-iron and alloys, aluminum and alloys, carbon steels, and fiber reinforced composites.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 14/178,628, filed on Feb. 12, 2014, the entirety of which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure is directed to indexable cutting inserts and toolholders for parallelogram-shaped cutting inserts with positive cuttinggeometry. In one non-limiting embodiment, cutting inserts according tothe present disclosure are particularly useful in peripheral rotarymilling applications for machining difficult-to-machine materials. Inanother non-limiting embodiment, cutting inserts according to thisdisclosure are uniquely useful in peripheral rotary milling applicationsthat generate segmented chips, for instance, when machining cast-ironand alloys, medium to high carbon steels, and fiber reinforced compositematerials.

2. Description of Related Art

It is well known that cutting inserts suffer from a limited service lifein peripheral rotary milling applications, especially when machiningdifficult-to-machine materials which include, for example, specialtymetals such as titanium and titanium alloys, nickel and nickel alloys,superalloys, certain exotic metals, and fiber reinforced polymercomposite. Cutting inserts comprising a positive cutting geometry on theaxial cutting face and the radial cutting face are commonly employed inmilling operations involving the use of a peripheral rotary tool holderwith an indexable capability. The positive cutting geometry of thecutting inserts reduces the cutting forces resulting in a more efficientmilling operation. A single-sided parallelogram-shaped cutting insert(often referred as A-Style insert) has a generally parallelogram-shapedprofile when viewed from a point above the insert's top surface, withtwo long sides forming two main cutting edges and two short sidesforming two minor cutting edges. These types of cutting inserts providemore efficient machining due to their positive cutting edges byproviding the capability of a larger depth of cut due to the longerparallelogram cutting edges.

Using double-sided cutting inserts is getting popular simply because thedoubled number of available cutting edges contributes to cost reductionbenefits for both cutting tool end users and cutting tool manufacturers.However, the geometric design of a double-sided cutting insert forperipheral rotary milling is a more challenging task compared to atraditional single-sided cutting insert, because of the complexity ofpositioning a double-sided cutting insert in an insert pocket on acutting tool holder in order to achieve sufficient positive cuttinggeometry all around the engaging cutting edge. A double-sidedparallelogram-shaped cutting insert has a generally parallelogram-shapedprofile when viewed from a point above the insert's top surface, withtwo long sides forming two main cutting edges and two short sidesforming two minor cutting edges on each of the top and bottom faces. Adouble-sided parallelogram-shaped cutting insert comprises a negativecutting geometry at least on the radial cutting face.

Efforts in the industry to develop new or improved parallelogram-shapedcutting inserts have been directed toward achieving reduced cuttingforces, reduced power consumption, increased cutting edge strength, andincreased tool life. From the point view of geometrical design,maintaining a positive cutting action has been a fundamental goal ofthese efforts. However, conventional parallelogram-shaped cuttinginserts for milling operation are only limited to either two positivecutting edges for a single-sided cutting insert or four generallynegative cutting edges for a double-sided cutting insert.

SUMMARY OF THE INVENTION

The invention provides an innovative and unique concept for designing aparallelogram-shaped cutting insert. The cutting insert of the presentinvention has a prismatic and/or cylindrical shape having multiplepositive cutting teeth with positive cutting geometry all around thecutting edges. In other words, each cutting tooth is equivalent to anindexable cutting edge for a single-sided parallelogram cutting insert(two positive cutting edges), however, the number of cutting teeth canbe three, four, five and even more. This allows more available long andpositive cutting edges than a traditional single-sided parallelogramcutting insert. In addition, a prismatic or cylindrical cutting insertaccording to this invention disclosure may demonstrate advantages over aprior art double-sided parallelogram cutting insert (negative geometryin general) by providing at least same number but positive long cuttingedges.

According to one non-limiting aspect of the present disclosure, acutting insert having prismatic and/or cylindrical (including tapered orconical) shape comprises multiple cutting teeth each being equivalent toa cutting edge of a single-sided parallelogram-shaped cutting insert(referred in cutting tool industries as A-style cutting insert havingtwo available cutting edges). A prismatic and cylindrical cuttingaccording to present invention has multiple indexable positive cuttingedges ranging from four to six or even more depending on the actualmilling applications. The prismatic and cylindrical cutting insert maybe used for machining a wide range of materials includingdifficult-to-machine materials, cast-iron and alloys, aluminum andalloys, carbon steels, and fiber reinforced composites.

A generally prismatic and cylindrical cutting insert according topresent invention disclosure comprises multiple indexable cutting teethand each cutting tooth comprises a top face; at least one radialclearance face intersecting the top face; at least one axial clearanceface intersecting the top face, and at least one conic clearance faceintersecting the top face and connecting the at least one radialclearance face and the at least one radial clearance face; and a longcutting edge at the intersection of the top face and the first radialclearance face, a curved cutting edge at the intersection of the topface and the first conic clearance face, and a straight cutting edge atthe intersection of the top face and the first axial clearance face.

Further, a milling tool holder according to present invention comprisesa shank; at least an insert-receiving pocket being built-in around theperiphery of the milling tool holder and comprising a bottom seatingface, a radial seating face and a peripheral seating face; at least aprismatic and cylindrical cutting insert comprising a top face; at leastone radial clearance face intersecting the top face; at least one axialclearance face intersecting the top face, and at least one conicclearance face intersecting the top face and connecting the at least oneradial clearance face and the at least one radial clearance face; and along cutting edge at the intersection of the top face and the firstradial clearance face, a curved cutting edge at the intersection of thetop face and the first conic clearance face, and a straight cutting edgeat the intersection of the top face and the first axial clearance face.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features and characteristics of the non-exhaustive andnon-limiting embodiments according to the present disclosure will bebetter understood by reference to the following figures, in which:

FIG. 1 is an embodiment of the prismatic cutting insert with fourindexable cutting teeth according to present invention disclosure withFIG. 1(a) for a three-dimensional perspective view and FIG. 1(b) for aside view.

FIG. 2 various sectional views of the prismatic cutting insert in FIG. 1with FIG. 2(a) for a side view and FIG. 2(b) for cross-section viewstaken along section lines A-A, B-B, C-C and D-D of FIG. 2(a).

FIG. 3 is a three-dimensional perspective view of an embodiment of acutting tool system comprising a tool holder and six prismatic cuttinginserts each having four cutting teeth (or indexable cutting edges)according to present invention disclosure.

FIG. 4 demonstrates how a prismatic cutting insert with multiple cuttingteeth is positioned on a tool holder with FIG. 4(a) for a side view andFIG. 4(b) for an enlarged view designated by the circle A in FIG. 4(a).

FIG. 5 is another embodiment of the prismatic cutting insert with fourindexable cutting teeth each having a coolant hole on the top faceaccording to present invention disclosure with FIG. 5(a) for athree-dimensional perspective view and FIG. 5(b) for a side view.

FIG. 6 is a three-dimensional perspective view of an embodiment of acutting tool system comprising a tool holder and six prismatic cuttinginserts each having four cutting teeth (or indexable cutting edges)according to present invention disclosure.

FIG. 7 is further another embodiment of the cylindrical cutting insertwith five indexable cutting teeth according to present inventiondisclosure.

FIG. 8 is a three-dimensional perspective view of another embodiment ofa cutting tool system comprising a tool holder, twelve cylindricalcutting, and twelve fastening screws.

FIG. 9 is a practical design example showing the front-end view of acutting tool system comprising a tool holder, twelve cylindrical cuttinginserts, and twelve screws.

FIG. 10 is further another embodiment of the prismatic cutting insertwith four indexable cutting teeth each having a built-in hard tool tipaccording to present invention disclosure with FIG. 10(a) for athree-dimensional perspective view and FIG. 10(b) for a side view.

FIG. 11 is an embodiment of the prismatic cutting insert with fourindexable cutting teeth without a facet or straight cutting edgeaccording to present invention disclosure with FIG. 11(a) for athree-dimensional perspective view and FIG. 11(b) for a side view.

FIG. 12 shows a three-dimensional perspective view and a front-end viewof a basic cylinder having a center axis and a center hole.

FIG. 13 shows a three-dimensional perspective view and a front-end viewof a basic tapered cylinder having a center axis and a center hole.

FIG. 14 shows a three-dimensional perspective view and a front-end viewof a basic cylindrical cutting insert having cylindrical (or conical)peripheral profile.

FIG. 15 shows a three-dimensional perspective view and a front-end viewof a basic cylindrical cutting insert having cylindrical (or conical)peripheral profile and blended nose corners.

FIG. 16 shows a three-dimensional perspective view and a front-end viewof a basic prismatic cutting insert having prismatic peripheral planarsurface and blended nose corners.

FIG. 17 shows a three-dimensional perspective view and a front-end viewof a basic prismatic and cylindrical cutting insert having combinedprismatic peripheral planar surface and cylindrical (or conical)peripheral profile.

FIG. 18 is a principle diagram showing a cylindrical cutting insert.

FIG. 19 shows a cylindrical cutting insert according to an embodiment ofthe invention with FIG. 19(a) for a three-dimensional perspective view,FIG. 19(b) for a side view, and FIG. 19(c) for a cross-sectional viewtaken along line C-C of FIG. 19(b).

FIG. 20 shows a position of the cylindrical cutting insert of FIG. 19when secured in an insert-receiving pocket of a tool holder with FIG.20(a) for a side view and FIG. 20(b) as a three-dimensional perspectiveview.

FIG. 21 shows a cylindrical cutting insert according to anotherembodiment of the invention with FIG. 21(a) for a three-dimensionalview. FIG. 21(b) for a side view and FIG. 21(c) as a cross-sectionalview taken along line D-D of FIG. 21(b).

DETAILED DESCRIPTION OF THE INVENTION

In the present description of non-limiting embodiments and in theclaims, other than in the operating examples or where otherwiseindicated, all numbers expressing quantities or characteristics ofingredients and products, processing conditions, and the like are to beunderstood as being modified in all instances by the term “about”.Accordingly, unless indicated to the contrary, any numerical parametersset forth in the following description and the attached claims areapproximations that may vary depending upon the desired properties oneseeks to obtain in the apparatus and methods according to the presentdisclosure. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as set forth herein supersedes anyconflicting material incorporated herein by reference. Any material, orportion thereof, that is said to be incorporated by reference herein,but which conflicts with existing definitions, statements, or otherdisclosure material set forth herein is only incorporated to the extentthat no conflict arises between that incorporated material and theexisting disclosure material.

Parallelogram-shaped cutting inserts are typically used in peripheralrotary milling due to their relatively larger depth of cut obtained bythe relatively longer cutting edge as compared to square cuttinginserts. Cutting tool life becomes a critical factor in efficientperipheral long-edge rotary milling applications for machiningdifficult-to-machine specialty metals and fiber reinforced compositematerials that are widely used in aerospace industries. Therefore, thereis a need for an improved design of parallelogram shaped cutting insertsand an associated tool holder. The innovative cutting insert presentedin this invention having prismatic and cylindrical shape is the first incutting tool industries for the category of parallelogram-shaped cuttinginserts and beyond, effectively providing more available indexablepositive cutting edges and economically benefiting cutting tool userswith longer tool life per cutting insert.

FIG. 1 is an embodiment of the prismatic cutting insert 10 with fourindexable cutting teeth according to present invention disclosure withFIG. 1(a) for a three-dimensional perspective view and FIG. 1(b) for aside view. The prismatic cutting insert 10 comprising four identicalpositive cutting teeth 11 a, 11 b, 11 c and 11 d, each of which isequivalent to an indexable cutting edge of a traditional single-sidedparallelogram-shaped cutting insert having only two indexable cuttingedges. The four cutting teeth are rotational symmetric about the centeraxis 12 of the center screw hole 13, thus providing four availableindexable cutting edges. The center screw hole 13 starts at the frontend face 14 and ends at the bottom face 15 of the cutting insert 10.Each positive cutting tooth, with 11 a as a representative, comprises atop face 21, a radial clearance face 23 having positive cutting geometry(i.e. positive radial cutting clearance face), a generally conicalclearance face 24 having positive cutting geometry (i.e. positivecutting clearance face), an axial clearance face 25 having positivecutting geometry (i.e. positive axial cutting clearance face), a rampingclearance face 26 (on cutting tooth 11 d in FIG. 1(a) due to invisibleon cutting tooth 11 a) and a bottom face 22 partially embraced by theedges 34, 35 and 36 (see FIG. 1(b) or FIG. 1(a) for the bottom face 22of cutting tooth 11 b). The top face 21 may be in a form of a planarsurface, a planar surface with an axial rake angle and/or a radial rakeangle, a chip groove or chip breaker, or a combination thereof. Acomplete cutting edge from a cutting tooth with 11 a comprises the mainlong cutting edge 31, a nose corner cutting edge 32, a straight cuttingedge 33 (often referred as facet edge or wiper edge), and a rampingcutting edge 39 as shown in FIG. 1(b). All the cutting clearance facesincluding ramping face 26, axial face 25, conical or cylindrical face24, and radial face 23 may be in the form of multiple cutting clearancefaces to provide additional clearance between the corresponding cuttingedges (i.e. 39, 33, 32 and 31) and the workpiece materials to bemachined. Above the top of the cutting tooth is a fluted surface 16providing a space for chip evacuation. The prismatic cutting insert 10will seat on its bottom flat face 15 when mounted on a tool holder.

FIG. 2(a) is a side view of the prismatic cutting insert 10 (in FIG. 1)showing multiple sectional lines. Section A-A in FIG. 2(b) shows asectioned view of all four positive cutting teeth 11 a, 11 b, 11 c and11 d of the cutting insert 10 through the middle of the cutting insert10 and perpendicular to the center axis of 12. Section B-B in FIG. 2(b)shows a sectioned view perpendicular to the main long cutting edge 31 ofthe cutting tooth 11 a of the prismatic cutting insert 10, wherein thecutting edge 31 has a positive radial clearance angle A_radial. SectionC-C in FIG. 2(b) shows a sectioned view approximately perpendicular tothe nose corner cutting edge 32 of the cutting tooth 11 a of theprismatic cutting insert 10, wherein the cutting edge 32 has a positiveclearance angle A_nose. Section D-D in FIG. 2(b) shows a sectioned viewperpendicular to the facet (or straight) cutting edge 33 of the cuttingtooth 11 a of the prismatic cutting insert 10, wherein the cutting edge33 has a positive clearance angle A_axial in the axial direction.

FIG. 3 is a three-dimensional perspective view of an embodiment of acutting tool system 50 comprising a tool holder 51 and six prismaticcutting inserts 61-66 each having four indexable cutting teeth (orcutting edges) according to present invention disclosure. The toolholder 51 has a center hole 53 and a cutting axis 52 which will beperpendicular to the surface to be machined and in alignment with therotating axis of a metal cutting machine tool. The tool holder 51 hassix identical insert-receiving pockets 54 which are evenly built-inaround the periphery of the tool holder 51. As a representative example,the prismatic cutting insert 61 is securely positioned in the pocket 54.At one time, only one cutting tooth (or one cutting edge) from aprismatic cutting insert is engaged in machining operation, for examplethe cutting tooth 61 a of the prismatic cutting insert 61 is an engagingcutting tooth. The positions of the six prismatic cutting inserts 61-66are rotationally symmetric about the cutting axis 52 of the tool holder51. As a representative example of the prismatic cutting insert 61, fourcutting teeth 61 a, 61 b, 61 c and 61 d are rotationally symmetric aboutthe center axis 71 of the prismatic and cylindrical cutting insert 61and each cutting tooth may be indexed about the center axis 71 to becomean engaging cutting edge. Similarly each cutting tooth of prismaticcutting inserts 62-66 may be indexed about its center axis 72-76 tobecome an engaging cutting edge, respectively. Above each pocket like 54are a fluted surface 55 and a coolant hole 56. The center axis 71 from aprismatic cutting insert 61 is not parallel to the cutting axis 52 ofthe tool holder 51.

FIG. 4 demonstrates how a prismatic cutting insert 61 (same as that inFIG. 3) with multiple positive cutting teeth 61 a-61 d is positioned onthe tool holder 51. For demonstration purpose, only one prismaticcutting insert 61 is shown in FIG. 4(a) where the cutting insert 61 ispositioned on the tool holder 51 by a tilt angle A_tilt of its centeraxis 71 with the cutting axis 52 of the tool holder 52. Also shown inFIG. 4(a) is a workpiece 80 to be machined and its top surface 81 isengaged with the cutting tooth 61 a. FIG. 4(_(b)) is a scale-up drawingshowing details of the positions of four cutting teeth 61 a, 61 b, 61 cand 61 d when the prismatic and cylindrical cutting insert 61 is mountedon the tool holder 51 as well as the positional relation of each cuttingtooth with the workpiece surface 81. The cutting tooth 61 a comprises afacet edge 83, a nose corner edge 84, a long edge 85 and a rampingcutting edge 86. The tilt angle A_tilt between the cutting axis 52 ofthe tool holder 51 and the center axis 71 of the prismatic cuttinginsert 61 is determined by the following equation:

A_tilt=f(A_facet_edge, Dis_tool_tip, A_long_edge)   (1)

where A_facet_edge is the angle between the facet edge (straight edge)83 and the workpiece surface 81, Dis_tool_tip is the minimum distancebetween a tool tip (cutting tooth 61 d being the case as shown in FIG.4(b)) and the workpiece surface 81, and A_long_edge is the angle formedbetween the long edge 85 of the cutting tooth 61 a and the workpiece topsurface 81. The Dis_tool_tip determines the range of allowed rampingangle and depth in a ramping cutting operation using the ramping cuttingedge $6.

FIG. 5 is another embodiment of the prismatic cutting insert 100 withfour indexable cutting teeth according to present invention disclosurewith FIG. 5(a) for a three-dimensional. perspective view and FIG. 5(b)for a side view. The prismatic cutting insert 100 comprising fouridentical positive cutting teeth 101, 102, 103 and 104, each of which isequivalent to an indexable cutting edge of a traditional single-sidedparallelogram-shaped cutting insert (having only two indexable cuttingedges). The four cutting teeth are rotational symmetric about the centeraxis 110 of the center screw hole 105, thus providing four indexableavailable cutting edges. Similar to the prismatic cutting insert 10shown in FIG. 1, a complete cutting edge 112 from the cutting tooth like101 of the prismatic cutting insert 10 typically comprises threesegments as indicated in FIG. 5(a). Also similar to the prismaticcutting insert 10 shown in FIG. 1, the cutting tooth 101 of theprismatic cutting insert 100 has typically three positive clearancefaces 114 as indicated in FIG. 5(a). However, a unique feature added tothe prismatic cutting insert 100 (see both FIG. 5(a) and FIG. 5(b)) isthe four identical through insert coolant holes 106, 107, 108 and 109extended from the top face of the corresponding cutting tooth, forexample the coolant hole 106 on the top face 113 of the cutting tooth101. Assuming the cutting edge 112 of the cutting insert 100 is anengaging cutting edge, the coolant will come out from the coolant hole107 from the cutting tooth 102, thus providing a more effective coolanttargeting at the front portion of cutting edge 112. There may be morethan one group of such through cutting insert coolant holes 106-109 on aprismatic cutting insert like the cutting insert 100.

FIG. 6 is a three-dimensional perspective view of an embodiment of acutting tool system 120 comprising a tool holder 121 and six prismaticcutting inserts 131-136 each having four cutting teeth (or indexablecutting edges) according to present invention disclosure. The toolholder 121 has a center hole 122 and a cutting axis 123 which will beperpendicular to the workpiece surface to be machined and in alignmentwith the rotating axis of a metal cutting machine tool. The tool holder121 has six identical insert-receiving pockets 141-146 where theprismatic cutting inserts 131-136 are mounted. For the purpose of easyclarification of the geometric construction of the pockets 141-146 builtin the tool holder 121, two prismatic cutting inserts 131 and 132 aretaken aside from their positions on the tool holder 121 respectively.Similar to the prismatic cutting insert 100 shown in FIG. 5, eachcutting insert 131-136 has a group of through cutting insert coolantholes, for example the four through cutting insert coolant holes 161-164on the cutting insert 131. As shown in FIG. 6, the pocket 141 in whichthe prismatic cutting insert 131 will be secured has a coolant outlet151 a on the pocket face 168 for through cutting insert coolant and anadditional conventional coolant outlet 151 b. Similarly, the pocket 142,in which the prismatic cutting insert 132 will be secured, also has acoolant outlet 152 a on the pocket face 168 for through insert coolantand an additional conventional coolant outlet 152 b. Further, theprismatic cutting insert 131 will be secured in the pocket 141 by ascrew (not shown) through the center hole 169 into the threaded hole 165in the pocket 141. The bottom face 160 of the prismatic cutting insert131 will seat on the bottom seating face 166 in the pocket 141. Inaddition, the top face (not shown) of the cutting tooth 131 b of theprismatic cutting insert 131 will be aligned with and seated on theradial seating face 168 in the pocket 141 and the bottom face (notshown) of the cutting tooth 131 a of the prismatic cutting insert 131will be aligned with and seated on the peripheral seating face 167 inthe pocket 141.

FIG. 7 is further another embodiment of the cylindrical cutting insert170 with five indexable cutting teeth according to present inventiondisclosure. The prismatic cutting insert 170 comprising five identicalpositive cutting teeth 181, 182, 183, 184 and 185, each of which isequivalent to an indexable cutting edge of a traditional single-sidedparallelogram-shaped cutting insert with only two indexable cuttingedges. The five cutting teeth are rotational symmetric about the centeraxis 172 of the center screw hole 171 which is extended from the frontface 188 to the bottom face 189, thus providing five indexable availablecutting edges. The bottom face 189 of the cutting insert 170 is usuallya flat face functioning as a seating face when be seated in acorresponding insert-receiving pocket on a tool holder. The cuttinginsert 171 has a generally cylindrical (including conical) shape witheach cutting tooth has a complete or partial cylindrical (conical)radial clearance surface, for instance, the cutting tooth 181 of thecylindrical cutting insert 170 has a cylindrical (conical) surface 192.In addition, the cutting tooth 181 has a top face 191, a bottom face195, an axial clearance face 194, and a nose corner clearance face 193.Each cutting tooth provides a complete cutting edge, for instance, thecutting tooth 181 of the cylindrical cutting insert 170 has a maincutting edge comprising a long cutting edge 198, a nose corner curvedcutting edge 197, and a facet (or straight) cutting edge 196. The nosecorner clearance face 193 is generally conical which is defined in thisinvention to include a non-tapered cylindrical face as a special casewhen the radius of the nose corner curved cutting edge 197 at the topface 191 is equal to that of the nose corner edge 199 at the bottom face195.

There is no upper limit of the number of cutting teeth for a prismaticcutting insert 10 shown in FIG. 1, the prismatic cutting insert 100illustrated in FIG. 5, and the cylindrical cutting insert 170 presentedin FIG. 7. It all depends how much space needed between the cuttingteeth in order to evacuate chips generated when machining a particularcategory of work materials. Specifically speaking, when machining thework materials that generate long chips like a kind ofdifficult-to-machine material, it may require fewer number of cuttingteeth for example three to five, however, when machining the workmaterials that generate segmented chips like a kind of cast iron andalloy, medium to high carbon steel or fiber reinforced composite, it maybe of great advantage to develop a prismatic or cylindrical cuttinginsert with more cutting teeth like five, six and even more.

Another unique feature of a prismatic and cylindrical cutting insert isthat the insert may be designed into a compact size with more indexablecutting edges for the applications of machining materials featured bysegmented or small chips. FIG. 8 is a three-dimensional perspective viewof another embodiment of a cutting tool system 200 comprising a toolholder 220, twelve cylindrical cutting inserts 201-212 similar to thecylindrical cutting insert 170 shown in FIG. 7, and twelve fasteningscrews (only screw 221 is shown). Each of the cutting inserts 201-212has five cutting teeth (or indexable cutting edges) according to presentinvention disclosure. As a representative example, the cylindricalcutting insert 201 in FIG. 8 has five cutting teeth (or indexablecutting edges) 201 a, 201 b, 201 c, 201 d, and 201 e each of which isindexable about the axis 227 of the center hole 228. The tool holder2211 has a center hole 225 and a cutting axis 226 which will beperpendicular to the workpiece surface to be machined and in alignmentwith the rotating axis of a metal cutting machine tool. The tool holder220 has twelve identical insert-receiving pockets (only pocket 222 isshown) where the prismatic cutting inserts 201-212 are mounted andsecured by a corresponding screw like screw 221. An exploded view of thescrew 221 and the cylindrical cutting insert 202 being moved up fromtheir original positions in the pocket 222 is created in FIG. 8 wherethe screw 221 will secure the cylindrical cutting insert 202 through thecenter hole 229 into the threaded hole 224 in the pocket 222 of the toolholder 220. The bottom face 230 of the cylindrical cutting insert 202will be seated against the bottom seating face 223 in the pocket 222. Inaddition, the top face (not shown) of the cutting tooth 202 b of thecylindrical cutting insert 202 will be aligned with and seated on theradial seating face 222 b in the pocket 222 and the bottom face (notshown) of the cutting tooth 202 a of the cylindrical cutting insert 202will be aligned with and seated on the peripheral seating face 222 a inthe pocket 222 on the tool holder 220.

Also, much more flutes can be created on the tool holder havingprismatic or cylindrical cutting inserts as compared with conventionalparallelogram cutting inserts either single-sided cutting insert withpositive geometric shape or double-sided cutting insert with negativegeometric shape. This is largely due to the general cylinder profile ofa prismatic and/or cylindrical cutting insert and the position andorientation of the prismatic or cylindrical cutting insert on the toolholder. As a practical design example shown in FIG. 9 for a front-endview of the cutting tool system 200 (as seen in FIG. 8) comprising atool holder 220, twelve cylindrical. cutting inserts 201-212, and twelvescrews 221 a-2211. As shown in FIG. 9 for a cutting diameter of only 50mm, the tool holder can hold twelve cylindrical cutting inserts havingan IC (inscribed circle) of 9 mm. This, in addition to more indexablecutting edges, may provide a significantly increased productivity interms of material removal rate per cutting tool in machining operationsthat need a long cutting edge from a parallelogram cutting insert.

FIG. 10 is further another embodiment of the prismatic cutting insert240 with four indexable positive cutting teeth according to presentinvention disclosure with. FIG. 10(a) for a three-dimensionalperspective view and FIG. 10(b) for a side view. The prismatic cuttinginsert 240 comprising four identical positive cutting teeth 241, 242,243 and 244 each of which has a hard tool bit 251-254 built onto thecutting tooth. The material of such a hard tool bit 251-254 may be PCD(Polycrystalline diamond), CBN (cubic boron nitride), etc. The fourcutting teeth 241-244 are rotational symmetric about the center axis 247of the center screw hole 246, thus providing four indexable availablecutting edges. Such a prismatic cutting insert 240 with a built-in PCDor CBN tool tip may be particularly applicable to the applications ofcomposite machining involving fiber reinforced composite material orcarbon fiber reinforced polymer widely used in aerospace industries.

FIG. 11 is an embodiment of the prismatic cutting insert with fourindexable cutting teeth according to present invention disclosure withFIG. 11(a) for a three-dimensional perspective view and FIG. 11(b) for aside view. The prismatic cutting insert 300 comprising four identicalpositive cutting teeth 301 a, 301 b, 301 c and 301 d, each beingequivalent to an indexable cutting edge of a traditional single-sidedparallelogram-shaped cutting insert having two indexable cutting edges.The four cutting teeth 301 a-301 d are rotational symmetric about thecenter axis 309 of the center screw hole 308, thus providing fouravailable indexable cutting edges. Each cutting tooth, with 301 a as arepresentative, comprises a top face 302, a radial face 303 havingpositive cutting geometry (i.e. positive radial cutting clearance face),a conical or cylindrical face 304 having positive geometry (i.e.positive conical cutting clearance face), an axial face 305 havingpositive geometry (i,e. positive axial cutting clearance face), and abottom face 314 (see dotted area in FIG. 11(b) or FIG. 11(a) for thebottom face 306 of the cutting tooth 301 b). The top face 302 may be ina form of a planar surface, a planar surface with an axial rake angleand a radial rake angle, a chip groove or chip breaker, or a combinedgeometry of all the above-described. A complete cutting edge from acutting tooth 301 a comprises a main long cutting edge 311 and a nosecorner edge 312. As a difference from the prismatic cutting insert 10 inFIG. 1, the prismatic cutting insert 300 lacks a facet or straightcutting edge. Above the top of the cutting tooth 301 a is a flutedsurface 316 providing a space for chip evacuation,

Certain non-limiting embodiments according to the present disclosureinclude a generally prismatic and cylindrical including tapered orconical parallelogram cutting insert having multiple identical cuttingteeth each comprising a top face; at least one radial clearance faceintersecting the top face; at least one axial clearance faceintersecting the top face, and at least one conic or cylindricalclearance face intersecting the top face and connecting the at least oneradial clearance face and the at least one axial clearance face; and amain cutting edge at the intersection of the top face and the firstradial clearance face, a curved cutting edge at the intersection of thetop face and first conic clearance face, and a straight cutting edge atthe intersection of the top face and the first axial clearance face. Thestraight cutting edge is often referred as facet or wiper edge that isperpendicular to the cutting axis of the associated tool holder wheremultiple parallelogram cutting inserts are mounted.

The term “prismatic” used in this invention disclosure is mainly basedon the theoretical description of “prism” which is defined in geometryas a polyhedron with n-sided polygonal base. Also in theory a polyhedronis defined as a solid in three dimensions with planar faces and straightedges and in cutting tool industries, such a definition may be tailoredto effectively describe the geometric features of a cutting tool byadding geometric attributes like curved edges, blended corners, groovedsurfaces, etc. The term “prismatic” is used to describe the multipleidentical cutting teeth symmetrically built around a center axis of theprismatic cutting insert. The term “cylindrical” used in this inventiondisclosure mainly means that the (outward) radial clearance surface ofeach cutting tooth from a cylindrical cutting insert is a taperedcylindrical or conical surface at the periphery. The concept of usingunique prismatic and cylindrical cutting inserts to provide positivecutting edge or positive cutting geometry for milling operationsaccording to this invention is the first in cutting tool industries ascompared with the conventional cutting inserts and tangential cuttinginserts, which are two major categories of milling cutting inserts. Someembodiments according to the present invention disclosure may have acombined shape of prismatic profile and cylindrical profile, each ofwhich has been described in details through FIGS. 1-11. In order tofurther clarify what a prismatic and cylindrical cutting insert is andwhy the term prismatic and cylindrical is used, FIGS. 12-17 demonstratestep by step the creation of a basic prismatic and cylindrical cuttinginsert.

As Step One a cylinder 350 is shown in FIG. 12 where the left side viewis a three-dimensional perspective view and the right side view is afront-end view. The cylinder 350 has a center axis 353, a center hole352 and a cylindrical surface 351 starting from front periphery 355 andending at back periphery 356 which is equal in diameter to the frontperiphery 355.

As Step Two the cylinder 350 in FIG. 12 is geometrically transformedinto a tapered cylindrical shape or a conical shape 360 as shown in FIG.13 where the left side view is a three-dimensional perspective view andthe right side view is a front-end view. The tapered (or conical)cylinder 360 has a center axis 363, a center hole 362 and a conicalsurface 361 starting from front periphery 365 and ending at backperiphery 366 which is smaller in diameter than the front periphery 365.

As Step Three the tapered cylinder 360 in FIG. 13 is furthergeometrically transformed into a cylindrical cutting insert 370 shown inFIG. 14 having a tapered cylindrical (or conical) peripheral profile371. The cylindrical cutting insert 370 has a center hole 372, a centeraxis 373, and five identical cutting teeth (or indexable cutting edges)370 a, 370 b, 370 c, 370 d and 370 e. As shown in both the left andright side views in FIG. 14, each cutting tooth 370 a-370 e of thecylindrical cutting insert 370 has the same tapered cylindrical (orconical) peripheral profile 371.

As Step Four the cylindrical cutting insert 370 in FIG. 14 is furthergeometrically transformed into a more reality cylindrical cutting insert380 shown in FIG. 15 by adding a blended nose corner 385 a-385 e foreach corresponding cutting tooth 380 a-380 e. The cylindrical cuttinginsert 380 has a center hole 382, a center axis 383, and five identicalcutting teeth (or indexable cutting edges) 380 a, 380 b, 380 c, 380 dand 380 e each having the same tapered cylindrical (or conical)peripheral profile 381 as shown in both the left and right side views ofFIG. 15.

As an alternative Step Four the cylindrical cutting insert 370 in FIG.14 may be geometrically transformed into prismatic cutting insert 390shown in FIG. 16 by adding a blended nose corner 395 a-395 e for eachcutting tooth 390 a-390 e. The prismatic cutting, insert 390 has acenter hole 392, a center axis 393, and five identical cutting teeth (orindexable cutting edges) 390 a, 390 b, 390 c, 390 d and 390 e eachhaving the same prismatic planar surface 391 a-391 e and with nooriginal cylindrical peripheral profile as shown in both the left andright side views of FIG. 16.

As an optional Step Five the cylindrical cutting insert 370 in FIG. 14may be further geometrically transformed into a prismatic andcylindrical cutting insert 400 shown in FIG. 17 by adding a blended nosecorner (not numbered) for each cutting tooth 400 a, 400 b, 400 c, 400 dand 400 e. The prismatic and cylindrical cutting insert 400 has a centerhole 406, a center axis 407, and five identical cutting teeth (orindexable cutting edges) 400 a-400 e each having the same prismaticplanar surface 401 a-401 e together with an original cylindrical(tapered or conical) peripheral profile 420 as shown in both the leftand right side views of FIG. 17. Therefore we define the cutting insertcreated according FIGS. 12-17 as a prismatic and cylindrical cuttinginsert.

In particular, the concept of cylindrical cutting insert having aplurality of long cutting edges comes from a simple idea, that is,convert a solid endmill having multiple flutes into a parallelogramcutting insert comprising long cutting edge. Each cutting tooth from asolid endmill can be converted into a positive cutting tooth mimicking asingle-sided. parallelogram cutting insert (referred as A-style cuttinginsert in cutting tool industries). Thus each cutting tooth of acylindrical cutting insert possesses all geometric features ofsingle-sided parallelogram cutting insert such as long cutting edge, 90degree shoulder cutting, ramping capability, chip groove, a wide rangeof nose corner radii and all around positive cutting clearance surfaces,however, the number of indexable cutting edges may be increased to, forexample, three, four, five and even more, as compared only two for acommercially available single-sided parallelogram cutting insert.

Furthermore, a cylindrical cutting insert has advantages over aprismatic cutting insert as presented earlier in FIGS. 1-6 from the viewpoint of the simplicity in cutting insert manufacturing. The cylindricalperiphery of a cylindrical cutting insert is easier to achieve betterdimensional accuracy and consistent indexability due to the fact thatall indexable cutting edges share the same circular periphery.

In the following FIGS. 18 to 20, a detailed description is provided topresent an embodiment based on this invention for a cylindrical cuttinginsert which demonstrates all geometric features that a commerciallyavailable single-sided parallelogram cutting insert possesses. FIG. 18is a principle diagram showing that a cylindrical cutting insertrepresented by a small broken line circle 505 is positioned in a cutterbody represented by the big arc 500 where the small circle 505 istangent to the big arc 500 and the center line 502 a representing acutting edge is aligned to the center line 504 of the big arc 500. As acomparison, the small solid line circle 501 represented anothercylindrical cutting insert is linearly offset by delta_X and delta_Yfrom the circle 505 while maintaining its cutting edge 502 b at thecenter line 504 of the arc 500. As seen from the detailed view the smallcircle 501 forms a sufficient positive cutting clearance 507 under thecutting point 506 against the big arc 500 while the small circle 505forms a very limited clearance 508. A cylindrical periphery may beeasier to manufacture than prismatic periphery thus may be a goodcandidate for fully pressed or fully injection molded cutting insert.The positional relationship of the small circle 501 is used for creatinga cylindrical cutting insert comprising a plurality of positive cuttingteeth presented in the following FIGS. 19-21.

FIG. 19 shows an embodiment according to this invention for acylindrical cutting insert 510 with FIG. 19(a) for a perspective view,FIG. 19(b) for a side view and FIG. 19(c) for a sectioned view fromsection C-C in FIG. 19(b). The cylindrical cutting insert 510 has agenerally tapered or conical profile from its front-end face 517 to therear-end face 518. The cylindrical cutting 510 comprises four identicaland indexable positive cutting teeth 511, 512, 513 and 514 which arerotational symmetric around the center axis 515 of the fastener bore516. Each cutting tooth 511 has a top face 521, a bottom face 522 (alsosee the bottom face 512 a from cutting tooth 512), a radial clearanceface 523 which is a portion of the tapered cylindrical periphery of thecylindrical cutting insert 510, a conical clearance face 524 which maybe in a form of cylindrical face in some cases, an axial clearance face525, and a ramping clearance face 526 (also see the ramping clearanceface 514 a on cutting tooth 514). Further each cutting tooth 511 of thecutting insert 510 comprises a major long cutting edge 531, a curvednose cutting edge 532, a straight cutting edge 533, and a rampingcutting edge 534 (also see the ramping cutting edge 514 b on cuttingtooth 514). In some embodiments, the number of straight cutting edgesand the number of curved cutting edges may be more than one. The topface 521 of the cutting tooth 511 comprise a chip groove or chip breaker538 as seen in both. FIG. 19(a) and FIG. 19(c), and in some embodimentsof this invention, the top face 521 may be in a form of a planarsurface, a planar surface with an axial rake angle and a radial rakeangle, a chip groove, a chip breaker, and a geometric combination of aplanar surface, or a chip groove and a chip breaker. In FIG. 19(b), theconical portion 539 of the fastener bore 516 of the cylindrical cuttinginsert 510 is at the middle of the cylindrical cutting insert 510 alongits center axis 515 thus providing a unique solution to avoid using along screw (not shown) in order to secure a cylindrical cutting insert510 into a threaded hole on a tool holder. The curved nose cutting edge532 has a wide range of nose radii of parallelogram cutting inserts thatmay be created by this invention. The space 529 between the top face 521of the cutting tooth 511 and the bottom face 512 a of an adjacentcutting tooth 512 automatically forms a cutting flute to evacuate chipsproduced during the machining, which may reduce a manufacturingoperation to create a flute on the tool holder in the case that a flutefrom a cutting tooth alone is sufficient to evacuate chips.

FIG. 20 demonstrates the position of a cylindrical cutting insert 510(same cutting insert as that in FIG. 19) when it is secured in aninsert-receiving pocket (not shown) of a tool holder with FIG. 20(a) fora side view and FIG. 20(b) for a front-end view. In FIG. 20(a), thevertical line 550 represents the cutting axis of a tool holder (notshown) where a cylindrical cutting insert 510 is mounted, the line 554represents the surface of a workpiece being machined, line 556represents a machined wall that is substantially perpendicular to theworkpiece surface 554, and line 555 represents the lowest positions ofthe non-engaging cutting teeth 512 and 514 when the cylindrical cuttinginsert 510 is positioned on the tool holder. In FIG. 20(b), the line 551represents the Y center line and line 552 represents the X center lineof the cutting diameter circle 553 of a tool holder. The centralposition of the cylindrical cutting insert 510 on a tool holder has anoffset delta_X and an offset delta_Y for the same reason as alreadydemonstrated in FIG. 18, that is, forming a positive radial clearancesurface between the cylindrical surface 523 and the cutting diametercircle 553 as shown in FIG. 20(b).

As shown in FIG. 20(a), the cylindrical cutting insert 510 is positionedon a tool holder in a way that the straight cutting edge 533 of theengaging cutting tooth 511 is perpendicular to the cutting axis 550 oraligned with the workpiece surface in order to produce good surfacefinish and meanwhile the long cutting edge 531 of the engaging cuttingtooth 511 will generate a substantially 90 degree wall 556 on theshoulder of the workpiece. The space between the workpiece surface 554and the fine 555 defined by the lowest non-engaging cutting teeth 512and 514 determines the range that the ramping cutting edge 534 of theengaging cutting tooth 511 is able to perform during a rampingoperation,

FIG. 21 shows another embodiment according to this invention for acylindrical cutting insert 610 with FIG. 21(a) for a perspective view,FIG. 21(b) for a side view and FIG. 21(c) for a sectioned view fromsection D-D in FIG. 21(b). The cylindrical cutting insert 610 is verysimilar to the cylindrical cutting insert 510 illustrated in FIG. 19except that each positive cutting tooth 611 of the cylindrical cuttinginsert 610 comprises two radial cutting clearance faces 623 a, 623 b,two conical or cylindrical cutting clearance faces 624 a, 624 b, and twoaxial cutting clearance faces 625 a, 625 b. Same as the cylindricalcutting insert 510 in FIG. 19, the cylindrical cutting insert 610 shownin FIG. 21 has a generally tapered or conical profile and comprises fouridentical and indexable cutting teeth 611, 612, 613 and 614 which arerotational symmetric around the center axis 615 of the fastener bore616. Each cutting tooth 611 comprises a main cutting edge 631, a curvedcutting edge 632, a straight (or wiper) cutting edge 633 and a rampingcutting edge 634, all at the top face 621 of the cutting tooth 611. Eachcutting tooth 611 has a top face 621, a bottom face 622, a planar radialclearance face 623 a extended from the main cutting edge 631 and acylindrical clearance face 623 b which is a portion of the originaltapered cylindrical periphery of the cylindrical cutting insert 610, aconical (or cylindrical) clearance face 624 a and a second conical (orcylindrical) clearance face 624 b, and an axial clearance face 625 a anda second axial clearance face 625 b, and a ramping clearance face 629(on cutting tooth 614 in FIG. 21(a) due to invisible on cutting tooth611).

Furthermore, certain non-limiting embodiments according to the presentinvention disclosure are related to prismatic and cylindrical cuttinginserts and associated tool holders for milling operations. It will beunderstood, however, that inserts and tool holders within the scope ofthe present invention disclosure may be embodied in forms and applied toend uses that are not specifically and expressly described herein. Forexample, one skilled in the art will appreciate that embodiments withinthe scope of the present disclosure and the following claims may bemanufactured as prismatic and cylindrical cutting inserts and/or toolholders adapted for other methods of removing metal from all types ofwork materials.

It will be understood that the present description illustrates thoseaspects of the invention relevant to a clear understanding of theinvention. Certain aspects that would be apparent to those of ordinaryskill in the art and that, therefore, would not facilitate a betterunderstanding of the invention have not been presented in order tosimplify the present description. Although only a limited number ofembodiments of the present invention are necessarily described herein,one of ordinary skill in the art will, upon considering the foregoingdescription, recognize that many modifications and variations of theinvention may be employed. All such variations and modifications of theinvention are intended to be covered by the following claims.

1. A prismatic and cylindrical cutting insert comprising: at least threecutting teeth, at least two of the three cutting teeth each comprising:a top face; a radial clearance face; an axial clearance face; a conicalclearance face; a long cutting edge at an intersection of the top faceand the radial clearance face; a nose corner cutting edge at anintersection of the top face and the conical clearance face; and astraight cutting edge at an intersection of the top face and the axialclearance face, wherein the top face comprises one of a planar surface,a planar surface with an axial. rake angle and a radial rake angle, achip groove, a chip breaker, or a combination thereof.
 2. The cuttinginsert of claim 1, wherein the plurality of cutting teeth arerotationally symmetric about a center axis of a center screw hole, 3.The cutting insert of claim 1, wherein a number of cutting teeth isbetween three and twenty.
 4. The cutting insert of claim 1, wherein atleast one cutting tooth lacks a straight cutting edge at theintersection of the top face and the first axial clearance face.
 5. Thecutting insert of claim 1, wherein at least one cutting tooth comprisesa built-in hard tool tip.
 6. The cutting insert of claim 1 furthercomprising at least three fluted surfaces, individual fluted surfacesbeing disposed between two of the cutting teeth.
 7. The cutting insertof claim 1, wherein at least one of the cutting teeth defines a coolanthole extending through the at least one cutting tooth.
 8. The cuttinginsert of claim 1 further comprising at least three bottom faces,individual bottom faces being disposed between adjacent cutting teeth.9. The cutting insert of claim 8, wherein an inscribed circle defined bythe bottom faces has a smaller diameter than a diameter of an inscribedcircle defined by the top faces.
 10. A prismatic and cylindrical cuttinginsert comprising: at least three cutting teeth, at least two of thethree cutting teeth each comprising: a top face; a radial clearanceface; an axial clearance face; a conical clearance face; a long cuttingedge at an intersection of the top face and the radial clearance face; anose corner cutting edge at an intersection of the top face and theconical clearance face; and a straight cutting edge at an intersectionof the top face and the axial clearance face, wherein the top facecomprises at one of a chip groove, a chip breaker, or a combinationthereof.
 11. The cutting insert of claim 10, wherein the plurality ofcutting teeth are rotationally symmetric about a center axis of a centerscrew hole.
 13. The cutting insert of claim 10, wherein a number ofcutting teeth is between three and twenty.
 14. The cutting insert ofclaim 10, wherein at least one cutting tooth lacks a straight cuttingedge at the intersection of the top face and the first axial clearanceface.
 15. The cutting insert of claim 10, wherein at least one cuttingtooth comprises a built-in hard tool tip.
 16. The cutting insert ofclaim 10 further comprising at least three fluted surfaces, individualfluted surfaces being disposed between two of the cutting teeth.
 17. Thecutting insert of claim 10, wherein at least one of the cutting teethdefines a coolant hole extending through the at least one cutting tooth.18. The cutting insert of claim 10 further comprising at least threebottom faces, individual bottom faces being disposed between adjacentcutting teeth.
 19. The cutting insert of claim 18, wherein an inscribedcircle defined by the bottom faces has a smaller diameter than adiameter of an inscribed circle defined by the top faces.
 20. A toolholder comprising: an insert-receiving pocket being built-in around aperiphery of said tool holder and comprising a bottom seating face, aradial seating face and a peripheral seating face; and a prismatic andcylindrical cutting insert mounted in the insert-receiving pocket, thecutting insert comprising at least three cutting teeth, at least two ofthe three cutting teeth each comprising: a top face; a radial clearanceface; an axial clearance face; a conical clearance face, a long cuttingedge at an intersection of the top face and the radial clearance face; anose corner cutting edge at an intersection of the top face and theconical clearance face; and a straight cutting edge at an intersectionof the top face and the axial clearance face. wherein the top facecomprises one of a planar surface, a planar surface with an axial rakeangle and a radial rake angle, a chip groove, a chip breaker, or acombination thereof.